1. Field of the Invention
The present invention relates to an image forming apparatus such as a laser printer and, more particularly, to an image forming apparatus for outputting a message such as a maintenance operation manual.
2. Description of the Related Art
Image formation in a conventional image forming apparatus such as a laser printer is performed by processes such as charging, exposure, development, transfer, separation, cleaning, and fixing. In such an image forming apparatus, a charging unit, an exposure unit, a developing unit, a transfer unit, a separation unit, a cleaning unit, and the like are sequentially arranged around a photosensitive drum body. In addition, this image forming apparatus includes a fixing unit for receiving a sheet from the separation unit. The units described above are selectively driven upon rotation of the photosensitive drum to perform the above image forming processes, thereby performing image formation.
The photosensitive drum, the developing unit, the fixing unit, and the like wear out over time, i.e., they are expendable. Replacement timings (life times) of these parts are determined in accordance with the frequencies of use. When the frequency of use of each part reaches a predetermined value, this part must be replaced with a new one. A corona wire of the charging unit and the like must be cleaned in accordance with a predetermined frequency of use. In order to perform the replacement of expendables and the cleaning operation of the corona wire and the like at optimal timings, a message representing a replacement or cleaning timing may be displayed on a display unit arranged in an operation panel to signal the need for replacement or cleaning to an operator.
Since the screen area of this display unit is generally small, such a message must be displayed with a symbol or short sentence. The operator, therefore may not accurately understand the content of the message. Even, if the operator understands the content of the message, he or she may not be familiar with replacement or cleaning procedures. In this case, an operation manual of this apparatus is prepared, and the operator performs replacement or cleaning in accordance with instructions described in this operation panel. It is, however, cumbersome to prepare the operation manual, find out a desired item, and read its contents. In addition, replacement or cleaning cannot always be performed immediately after the message is displayed, resulting in inconvenience. When replacement or cleaning is not performed at an optimal timing, the corresponding part may fail, and satisfactory image formation may not be performed.
When a copy count reaches a predetermined number, e.g., 5,000, a cleaning message for the corona wire is displayed. In this case, when image data from a host unit is being printed, the operator may misunderstand that printing of this image data must be interrupted. In addition, the operator may be afraid of degradation of printing quality.